Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;

vector<int> mh={0,1,-1,0};
vector<int> mw={1,0,0,-1};

int main()
{
int H,W,ans,h,w,nh,nw;scanf("%d %d",&H,&W);ans=H*W;
vector<vector<char>> s(H,vector<char>(W));vector<vector<int>> dis(H,vector<int>(W,0));
for(int i=0;i<H;i++)for(int j=0;j<W;j++){cin>>s[i][j];if(s[i][j]=='#')ans--;}
queue<pair<int,int>> que;que.push(make_pair(0,0));
while(!que.empty())
{
  h=que.front().first,w=que.front().second;que.pop();
  if(s[h][w]=='#')continue;
  s[h][w]='#';
  for(int i=0;i<4;i++)
  {
    nh=h+mh[i],nw=w+mw[i];
    if(nh<0||nh>H-1||nw<0||nw>W-1)continue;
    if(s[nh][nw]=='#')continue;
    dis[nh][nw]=dis[h][w]+1;
    que.push(make_pair(nh,nw));
  }
}
ans=ans-1-dis[H-1][W-1];
if(!dis[H-1][W-1])ans=-1;
printf("%d\n",ans);
}